synapse_row.h File Reference

implementation for handling the processing of synapse rows. More...

#include <common/neuron-typedefs.h>

Go to the source code of this file.

Data Structures
struct	synapse_row_plastic_part_t
	The type of the plastic-plastic part of the row. More...
struct	synapse_row_fixed_part_t
	The type of the fixed part of the row. The fixed-plastic part follows. More...

Macros
#define	SYNAPSE_WEIGHT_BITS   16
	how many bits the synapse weight will take
#define	N_SYNAPSE_ROW_HEADER_WORDS   3
	Number of header words per synaptic row.

Typedefs
typedef uint16_t	control_t
	Define the type of the control data.

Functions
static size_t	synapse_row_plastic_size (const synaptic_row_t row)
	Get the size of the plastic region.
static synapse_row_plastic_data_t *	synapse_row_plastic_region (synaptic_row_t row)
	Get the address of the plastic region.
static synapse_row_fixed_part_t *	synapse_row_fixed_region (synaptic_row_t row)
	Get the address of the non-plastic (or fixed) region.
static size_t	synapse_row_num_fixed_synapses (const synapse_row_fixed_part_t *fixed)
	Get the number of fixed synapses in the row.
static size_t	synapse_row_num_plastic_controls (const synapse_row_fixed_part_t *fixed)
	Get the number of plastic controls in the row.
static control_t *	synapse_row_plastic_controls (synapse_row_fixed_part_t *fixed)
	Get the array of plastic controls in the row.
static uint32_t *	synapse_row_fixed_weight_controls (synapse_row_fixed_part_t *fixed)
	The array of fixed weights in the row.
static index_t	synapse_row_sparse_index (uint32_t x, uint32_t synapse_index_mask)
	Get the index.
static index_t	synapse_row_sparse_type (uint32_t x, uint32_t synapse_index_bits, uint32_t synapse_type_mask)
	Get the type code.
static index_t	synapse_row_sparse_type_index (uint32_t x, uint32_t synapse_type_index_mask)
	Get the type and index.
static index_t	synapse_row_sparse_delay (uint32_t x, uint32_t synapse_type_index_bits, uint32_t synapse_delay_mask)
	Get the delay from an encoded synapse descriptor.
static weight_t	synapse_row_sparse_weight (uint32_t x)
	Get the weight from an encoded synapse descriptor.
static input_t	synapse_row_convert_weight_to_input (weight_t weight, uint32_t left_shift)
	Converts a weight stored in a synapse row to an input.
static index_t	synapse_row_get_ring_buffer_index (uint32_t simulation_timestep, uint32_t synapse_type_index, uint32_t neuron_index, uint32_t synapse_type_index_bits, uint32_t synapse_index_bits, uint32_t synapse_delay_mask)
	Get the index of the ring buffer for a given timestep, synapse type and neuron index.
static index_t	synapse_row_get_ring_buffer_index_time_0 (uint32_t synapse_type_index, uint32_t neuron_index, uint32_t synapse_index_bits)
	Get the index of the ring buffer for time 0, synapse type and neuron index.
static index_t	synapse_row_get_first_ring_buffer_index (uint32_t simulation_timestep, uint32_t synapse_type_index_bits, int32_t synapse_delay_mask)
	Get the index of the first ring buffer for a given timestep.
static index_t	synapse_row_get_ring_buffer_index_combined (uint32_t simulation_timestep, uint32_t combined_synapse_neuron_index, uint32_t synapse_type_index_bits, uint32_t synapse_delay_mask)
	Get the index of the ring buffer for a given timestep and combined synapse type and neuron index (as stored in a synapse row)

Detailed Description

implementation for handling the processing of synapse rows.

Synapse Row Representation

|       Weight      |       Delay      |  Synapse Type   |   Neuron Index   |
|-------------------|------------------|-----------------|------------------|
|SYNAPSE_WEIGHT_BITS|SYNAPSE_DELAY_BITS|SYNAPSE_TYPE_BITS|SYNAPSE_INDEX_BITS|
|                   |                  |       SYNAPSE_TYPE_INDEX_BITS      |

The API interface supports:

• synapse_row_plastic_size()
• synapse_row_plastic_region()
• synapse_row_fixed_region()
• synapse_row_num_fixed_synapses()
• synapse_row_num_plastic_controls()
• synapse_row_plastic_controls()
• synapse_row_fixed_weight_controls()
• synapse_row_sparse_index()
• synapse_row_sparse_type()
• synapse_row_sparse_type_index()
• synapse_row_sparse_delay()
• synapse_row_sparse_weight()

Data Structure

The data structure layout supported by this API is designed for mixed plastic and fixed synapse rows.

The data structure is treated as an array of 32-bit words. Special meanings are ascribed to the 0th and 1st elements of the array.

We are expecting the original source address in SDRAM to be in row[0]. The number of array elements in the plastic region is held in the upper part of row[1]. A tag to indicate the nature of the synaptic row structure is held in the lower part of row[1].

  0:  [ N = <plastic elements>         | <tag> ]
  1:  [ First word of plastic region           ]
  ...
  N:  [ Last word of plastic region            ]
N+1:  [ First word of fixed region             ]
  ...
 M:   [ Last word of fixed region              ]

Fixed and Fixed-Plastic Regions

Within the fixed-region extracted using the above API, fixed[0] contains the number of 32-bit fixed synaptic words, fixed[1] contains the number of 16-bit plastic synapse control words. (The weights for the plastic synapses are assumed to be stored in some learning-rule-specific format in the plastic region)

  0:           [ F = Num fixed synapses                                    ]
  1:           [ P = Size of plastic region in HALF-WORDS                  ]
  2:           [ First fixed synaptic word                                 ]
  ...
F+1:           [ Last fixed synaptic word                                  ]
F+2:           [ 1st plastic synapse control word|2nd plastic control word ]
  ...
F+1+ceil(P/2): [ Last word of fixed region                                 ]

Note that P is effectively rounded up to a multiple of two for storage purposes.

Definition in file synapse_row.h.

---

Data Structure Documentation

synapse_row_plastic_part_t

struct synapse_row_plastic_part_t

The type of the plastic-plastic part of the row.

Definition at line 112 of file synapse_row.h.

Data Fields
size_t	size	The number of plastic words in data
uint32_t	data[]	The plastic words, followed by the fixed part.

synapse_row_fixed_part_t

struct synapse_row_fixed_part_t

The type of the fixed part of the row. The fixed-plastic part follows.

Definition at line 118 of file synapse_row.h.

Data Fields
size_t	num_fixed	The number of fixed synapses in data
size_t	num_plastic	The number of plastic controls in data
uint32_t	data[]	The data, first the fixed then the plastic.

Macro Definition Documentation

SYNAPSE_WEIGHT_BITS

#define SYNAPSE_WEIGHT_BITS   16

how many bits the synapse weight will take

Definition at line 95 of file synapse_row.h.

N_SYNAPSE_ROW_HEADER_WORDS

#define N_SYNAPSE_ROW_HEADER_WORDS   3

Number of header words per synaptic row.

Definition at line 109 of file synapse_row.h.

Typedef Documentation

control_t

typedef uint16_t control_t

Define the type of the control data.

Definition at line 106 of file synapse_row.h.

Function Documentation

synapse_row_plastic_size()

static size_t synapse_row_plastic_size ( const synaptic_row_t  row )

inlinestatic

Get the size of the plastic region.

Parameters

[in]

row

The synaptic row

Returns

The size of the plastic region of the row

Definition at line 129 of file synapse_row.h.

synapse_row_plastic_region()

static synapse_row_plastic_data_t * synapse_row_plastic_region ( synaptic_row_t  row )

inlinestatic

Get the address of the plastic region.

Parameters

[in]

row

The synaptic row

Returns

Pointer to the plastic region of the row

Definition at line 138 of file synapse_row.h.

synapse_row_fixed_region()

static synapse_row_fixed_part_t * synapse_row_fixed_region ( synaptic_row_t  row )

inlinestatic

Get the address of the non-plastic (or fixed) region.

Parameters

[in]

row

The synaptic row

Returns

Address of the fixed region of the row

Definition at line 147 of file synapse_row.h.

synapse_row_num_fixed_synapses()

static size_t synapse_row_num_fixed_synapses ( const synapse_row_fixed_part_t *  fixed )

inlinestatic

Get the number of fixed synapses in the row.

Parameters

[in]

fixed

The fixed region of the synaptic row

Returns

Size of the fixed region of the row (in words)

Definition at line 156 of file synapse_row.h.

synapse_row_num_plastic_controls()

static size_t synapse_row_num_plastic_controls ( const synapse_row_fixed_part_t *  fixed )

inlinestatic

Get the number of plastic controls in the row.

Parameters

[in]

fixed

The fixed region of the synaptic row

Returns

Size of the fixed-plastic region of the row (in half words)

Definition at line 164 of file synapse_row.h.

synapse_row_plastic_controls()

static control_t * synapse_row_plastic_controls ( synapse_row_fixed_part_t *  fixed )

inlinestatic

Get the array of plastic controls in the row.

Parameters

[in]

fixed

The fixed region of the synaptic row

Returns

Address of the fixed-plastic region of the row

Definition at line 172 of file synapse_row.h.

synapse_row_fixed_weight_controls()

static uint32_t * synapse_row_fixed_weight_controls ( synapse_row_fixed_part_t *  fixed )

inlinestatic

The array of fixed weights in the row.

Parameters

[in]

fixed

The fixed region of the synaptic row

Returns

Address of the fixed-fixed region of the row

Definition at line 180 of file synapse_row.h.

synapse_row_sparse_index()

static index_t synapse_row_sparse_index ( uint32_t  x, uint32_t  synapse_index_mask  )

inlinestatic

Get the index.

Parameters

[in]	x	The value to decode
[in]	synapse_index_mask	Mask for the synapse index (depends on type)

Returns

the index

Definition at line 190 of file synapse_row.h.

synapse_row_sparse_type()

static index_t synapse_row_sparse_type ( uint32_t  x, uint32_t  synapse_index_bits, uint32_t  synapse_type_mask  )

inlinestatic

Get the type code.

Parameters

[in]	x	The value to decode
[in]	synapse_index_bits	Number of bits for the synapse index (depends on type)
[in]	synapse_type_mask	Mask for the synapse type (depends on type)

Returns

the type code

Definition at line 201 of file synapse_row.h.

synapse_row_sparse_type_index()

static index_t synapse_row_sparse_type_index ( uint32_t  x, uint32_t  synapse_type_index_mask  )

inlinestatic

Get the type and index.

Parameters

[in]	x	The value to decode
[in]	synapse_type_index_mask	Mask for the synapse type and index (depends on type)

Returns

the type and index (packed in the low bits of a word)

Definition at line 211 of file synapse_row.h.

synapse_row_sparse_delay()

static index_t synapse_row_sparse_delay ( uint32_t  x, uint32_t  synapse_type_index_bits, uint32_t  synapse_delay_mask  )

inlinestatic

Get the delay from an encoded synapse descriptor.

Parameters

[in]	x	The value to decode
[in]	synapse_type_index_bits	Number of bits for the synapse type and index (depends on type)
[in]	synapse_delay_mask	The mask for selecting the bits of the delay

Returns

the delay

Definition at line 222 of file synapse_row.h.

synapse_row_sparse_weight()

static weight_t synapse_row_sparse_weight ( uint32_t  x )

inlinestatic

Get the weight from an encoded synapse descriptor.

Parameters

[in]

x

The value to decode

Returns

the weight

Definition at line 230 of file synapse_row.h.

synapse_row_convert_weight_to_input()

static input_t synapse_row_convert_weight_to_input ( weight_t  weight, uint32_t  left_shift  )

inlinestatic

Converts a weight stored in a synapse row to an input.

Parameters

[in]	weight	the weight to convert in synapse-row form
[in]	left_shift	the shift to use when decoding

Returns

the actual input weight for the model

Definition at line 238 of file synapse_row.h.

synapse_row_get_ring_buffer_index()

static index_t synapse_row_get_ring_buffer_index ( uint32_t  simulation_timestep, uint32_t  synapse_type_index, uint32_t  neuron_index, uint32_t  synapse_type_index_bits, uint32_t  synapse_index_bits, uint32_t  synapse_delay_mask  )

inlinestatic

Get the index of the ring buffer for a given timestep, synapse type and neuron index.

Parameters

[in]	simulation_timestep	The timestep
[in]	synapse_type_index	The synapse type index
[in]	neuron_index	The neuron index
[in]	synapse_type_index_bits	Number of bits for type and index
[in]	synapse_index_bits	Number of bits for index
[in]	synapse_delay_mask	Mask for delay

Returns

Index into the ring buffer

Definition at line 259 of file synapse_row.h.

synapse_row_get_ring_buffer_index_time_0()

static index_t synapse_row_get_ring_buffer_index_time_0 ( uint32_t  synapse_type_index, uint32_t  neuron_index, uint32_t  synapse_index_bits  )

inlinestatic

Get the index of the ring buffer for time 0, synapse type and neuron index.

Parameters

[in]	synapse_type_index	The synapse type index
[in]	neuron_index	The neuron index
[in]	synapse_index_bits	Number of bits for index

Returns

Index into the ring buffer

Definition at line 274 of file synapse_row.h.

synapse_row_get_first_ring_buffer_index()

static index_t synapse_row_get_first_ring_buffer_index ( uint32_t  simulation_timestep, uint32_t  synapse_type_index_bits, int32_t  synapse_delay_mask  )

inlinestatic

Get the index of the first ring buffer for a given timestep.

Parameters

[in]	simulation_timestep	The timestep
[in]	synapse_type_index_bits	Number of bits for type and index
[in]	synapse_delay_mask	Mask for delay

Returns

Index into the ring buffer

Definition at line 285 of file synapse_row.h.

synapse_row_get_ring_buffer_index_combined()

static index_t synapse_row_get_ring_buffer_index_combined ( uint32_t  simulation_timestep, uint32_t  combined_synapse_neuron_index, uint32_t  synapse_type_index_bits, uint32_t  synapse_delay_mask  )

inlinestatic

Get the index of the ring buffer for a given timestep and combined synapse type and neuron index (as stored in a synapse row)

Parameters

[in]	simulation_timestep	The timestep
[in]	combined_synapse_neuron_index
[in]	synapse_type_index_bits	Number of bits for type and index
[in]	synapse_delay_mask	Mask for delay

Returns

Index into the ring buffer

Definition at line 298 of file synapse_row.h.